Various forms of audiovisual display systems which receive display information via electromagnetic transmission have been known to the art. One common example is a television, where the information to be displayed is transmitted from a broadcaster, cable head or other source by electromagnetic communication.
The earliest televisions utilized a single tuner connected to an antenna. The antenna would receive the transmitted electromagnetic information at various frequencies, and the tuner would be used to select a desired channel. Such systems were straightforward in that the information transmitted over the various channels was fully available for display on the television.
Over time, television signals were transmitted over cable. The use of cable provided for increased bandwidth compared to the prior systems, and afforded information providers the opportunity to provide more channels to the customer. Cable systems typically included various levels of programming, often offering a basic package which included those channels which were available through non-cable reception, namely, the publicly available or "free" channels. Further, cable systems often provided various "premium" channels, for which a cable subscriber was billed an additional amount beyond the basic services. Typically, a cable box is provided from the cable company to the customer which receives the cable information and serves as a channel selector for provision of the channel to the television. Ordinarily, a channel is selected for communication between the cable box and the television, often channel 3 as that channel is not typically utilized in public, over the air transmissions. The cable box serves as a decoder or descrambler for the various premium channels. Selective accessing of premium channels may be accomplished by the cable company, either locally or through the cable connection, programming the cable box. By doing so, the cable box maintains a list of entitled or accessible channels.
Televisions having two tuners are known in the art. FIG. 1 shows a simplified diagrammatic view of a dual tuner system. A television 10 includes a display 12. A first tuner 14 and a second tuner 24 are labeled tuner one and tuner two, respectively (though the designations may be reversed). The first tuner 14 has an input 16 adapted to be coupled to a source of picture information, such as supplied from cable box 30. A selector 32 (shown diagrammatically in FIG. 1) may provide a selective connection between the first tuner output 18 and the display 12. Similarly, the second tuner 24 receives as input 26 a signal from any number of sources, as shown in FIG. 1 being adapted to receive the cable input 34. The selector 32 may be selectively coupled to the tuner two output 28 to display the information from tuner two 24 on the display 12. While not shown in the simplified diagrammatic view in FIG. 1, such dual tuner televisions 10 may be used in picture-in-picture systems wherein a first display 12 further includes a reduced sized picture 36. Tuner one 14 would then supply the display information for the main display 12 and tuner two would supply the picture information for the reduced sized picture 36.
In typical operation, tuner one 14 is set to a selected channel, e.g., channel 3, which receives the output of the cable box 30 on that selected channel. The tuning of the system is then performed by tuning the cable box 30. The combined system of the cable box 30 and tuner one 14 serve to select the channel on the cable box 30, and to provide it to selector 32 via tuner one 14. Channel selection is typically made via the cable remote control 40.
Historically, such a dual tuner television system 10 when operated with a cable box 30, required multiple remote controls 40, 42. A cable remote 40 was used principally for purposes of channel changing. A television remote control 42 was principally used to change between tuner one 14 and tuner two 24, as well as to adjust the volume, set color levels and cause other television related features to be set or adjusted.
Recently, efforts have been made to reduce the number of remote controls required for operation of the television 10 and cable box 30. One effort utilizes the television 10 to control the cable box 30 under operation of a single remote control. When a request for a channel change is sent from the remote control 42 to the television 10, the television 10 in turn communications the channel change request to the cable box 30. Since no feedback is provided from the cable box 30 to the television 10 in such systems, it has proved necessary to provide control information from the television 10 to the cable box 30 in a relatively slow manner. Often, this control information transfer slows channel changing by a factor of 10.
FIG. 2 shows a chronologic display of channel entry, with time going from the left to the right. In order to effect a first channel change 50, the television 10 sends a first digit to the cable box 30 at a time designated by marker 52. At a later time designated by marker 54, the television 10 sends a second digit to the cable box 30. At time indicated by marker 56, the television 10 sends an enter command to the cable box 30. Finally, at time indicated by marker 58, the cable box 30 actually tunes. Thus, the cumulative time from the initiation of a request until actual changing of the cable box 30 can be significant, in current practice taking on the order of 2 seconds. When scrolling through channels, such as through the use of the up channel button or in reviewing favorite channel lists, the time becomes cumulative, and is often viewed as a significant annoyance to the viewer. As shown in FIG. 2, from the first change 50 to the fifth change 60, intervening changes are of substantially equal length.
Despite the desirability of having a two tuner system which may be controlled by a single remote, yet which does not suffer from the disadvantage of slow tuning, no optimal system has been yet presented. The system of this invention seeks to remedy those deficiencies.